arm64: entry: Clean out some indirection

arm64: entry: Clean out some indirection

The conversion to generic IRQ entry left some functions
in the EL1 (kernel) IRQ entry path very shallow, so drop
the __inner_functions() where appropriate, saving some
time and stack.

This is not a fix but an optimization.

Drop stale comments about irqentry_enter/exit() while we
are at it.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>